/*
 * @Author: WuFeng <763467339@qq.com>
 * @Date: 2022-11-07 19:04:45
 * @LastEditTime: 2023-02-14 17:53:50
 * @LastEditors: WuFeng <763467339@qq.com>
 * @Description: 页面添加水印效果
 * @document https://blog.csdn.net/Jie_1997/article/details/120085074
 * @FilePath: \vue3-element-plus-web\src\plugins\watermark.js
 * @Copyright 版权声明
 * @示例： 在项目APP.vue中引用
      import watermark from '@/plugins/watermark.js'

      watch: {
        userinfo: {
          deep: true,
          handler(val) {
            watermark.set(`${val.name} ${val.account}`)
          }
        }
      },
      beforeUnmount() {
        watermark.set('')
      },
 *
 */
const watermark = {}

const setWatermark = (text, sourceBody) => {
  const id =
    Math.random() * 10000 +
    '-' +
    Math.random() * 10000 +
    '/' +
    Math.random() * 10000

  if (document.getElementById(id) !== null) {
    document.body.removeChild(document.getElementById(id))
  }

  const can = document.createElement('canvas')
  can.width = 300 //设置水印之间的左右间距
  can.height = 100 //设置水印之间的上下间距

  const cans = can.getContext('2d')
  cans.rotate((-20 * Math.PI) / 180)
  cans.font = '15px Vedana'
  cans.fillStyle = 'rgba(0, 0, 0, .1)'
  cans.textAlign = 'left'
  cans.textBaseline = 'Middle'
  cans.fillText(text, can.width / 20, can.height)

  const water_div = document.createElement('div')
  water_div.id = id
  water_div.className = 'watermarkClass'
  water_div.style.pointerEvents = 'none'
  water_div.style.background =
    'url(' + can.toDataURL('image/png') + ') left top repeat'
  if (sourceBody) {
    water_div.style.width = '100%'
    water_div.style.height = '100%'
    sourceBody.appendChild(water_div)
  } else {
    water_div.style.top = '3px'
    water_div.style.left = '0px'
    water_div.style.position = 'fixed'
    water_div.style.zIndex = '100000'
    water_div.style.width = document.documentElement.clientWidth + 'px'
    water_div.style.height = document.documentElement.clientHeight + 'px'
    document.body.appendChild(water_div)
  }

  return id
}

/**
 *  该方法只允许调用一次
 *  @param:
 *  @text == 水印内容
 *  @sourceBody == 水印添加的位置，不传就是body
 * */
watermark.set = (text, sourceBody) => {
  const domArr = Array.from(document.getElementsByClassName('watermarkClass'))
  for (let i = 0; i < domArr.length; i++) {
    const element = domArr[i]
    // element.parentNode.removeChild(element);
    element.remove()
  }
  if (text === '') {
    return
  }
  setWatermark(text, sourceBody)
  // let id = setWatermark(text, sourceBody);
  // setInterval(() => {
  //   if (document.getElementById(id) === null) {
  //     id = setWatermark(text, sourceBody);
  //   }
  // }, 2000);
  // window.onresize = () => {
  //   setWatermark(text, sourceBody);
  // };
}

export default watermark
